'ходишь' implies repetative process here. 'идёшь' implies continuous process. Difference is subtle, but it matters here. "Will you go to the univercity today?" vs "Are you visiting univercity (several times) today?". Such phrase is legal as is but it means different thing.

Alex80
These verbs are called multidirectional (like "ходить", simple aspect) and unidirectional (like "идти", continuous aspect):
(1) "Ходишь в университет" - multidirectional (or, like you say, used to show a repeated action - simple aspect, in terms of English grammar);
(2) "Идёшь в университет" - unidirectional (or used to show a one-time/single action - continuous aspect). In this case, very similar to English "Are you going to university today?" (continuous aspect, as we know, shows an intended future action, not only the current one)